Comparable outcomes for TBI-based versus treosulfan based conditioning prior to allogeneic hematopoietic stem cell transplantation in AML and MDS patients

Allogeneic hematopoietic stem cell transplantation (allo-HCT) is a standard treatment for patients with AML and MDS. The combination of fractionated total body irradiation(8GyTBI/Flu) with fludarabine is an established conditioning regimen, but fludarabine/treosulfan(Flu/Treo) constitutes an alternative in older/comorbid patients. We conducted a retrospective analysis of 215 AML(in CR) and 96 MDS patients undergoing their first allo-HCT between 2011 and 2022, identifying 53 matched Flu/Treo and 8GyTBI/Flu patients through propensity score matching. Median follow-up of survivors was 3.3 years and 4.1 years. For the Flu/Treo group, 1-year non-relapse mortality (2% vs. 10%, p = 0.03) was lower, while 1-year relapse incidence (16% vs. 13%, p = 0.81) was similar. Three-year outcomes, including relapse-free survival and graft-versus-host disease incidence, were comparable (OS: 81% vs. 74%, p = 0.70; RFS: 78% vs. 66%, p = 0.28; chronic GvHD: 34% vs. 36%, p = 0.97; acute GvHD (100 days): 11% vs. 23%, p = 0.11). Multivariable analysis, considering age, ECOG, HCT-CI, and MRD status, revealed no associations with main outcomes. Dose-reduced conditioning with Flu/Treo or 8GyTBI/Flu demonstrated favorable and comparable survival rates exceeding 70% at 3 years with 1-year NRM rates below 10% and low relapse rates in the matched cohort. These data underline the need for further evaluation of TBI and Treo-based conditionings in prospective trials.

Chimeric antigen receptor-T cell therapy shows similar efficacy and toxicity in patients with diffuse large B-cell lymphoma aged 70 and older compared to younger patients: A multicenter cohort study

CD19-directed chimeric antigen receptor (CAR)-T cell therapy has become a standard treatment for relapsed/refractory diffuse large B-cell lymphoma (r/r DLBCL). While the benefits of CAR-T cell treatment are clear in the general patient population, there remains a relative scarcity of real-world evidence regarding its efficacy and toxicity in patients (pts) aged ≥70 years with DLBCL. We conducted a multicenter retrospective analysis including 172 r/r DLBCL pts with CAR-T cell treatment, axicabtagene ciloleucel or tisagenlecleucel, between 2019 and 2023 at three tertiary centers. Pts were grouped by age at CAR-T infusion (<70 vs. ≥70 years). Subsequently, descriptive and survival analyses, including propensity score matching, were performed to compare outcomes between both age groups. We identified 109 pts aged <70 and 63 pts aged ≥70 years. Overall response rates for both age groups were comparable (77.7% vs. 78.3%; p = 0.63). With a median follow-up of 8.3 months, median progression-free survival was 10.2 months (95% confidence interval [CI]: 6.5-21.8) and 11.1 months (95% CI: 4.9-NR) (p = 0.93) for both cohorts. Median overall survival reached 21.8 months (95% CI: 11.8-NR) and 34.4 months (95% CI: 10.1-NR) (p = 0.97), respectively. No significant differences in the incidence of cytokine release syndrome (p = 0.53) or grade ≥3 neurotoxicity (p = 0.56) were observed. Relapse and nonrelapse mortality were not significantly different between both groups. Our findings provide additional support that CAR-T cell therapy is feasible and effective in patients with r/r DLBCL aged 70 years or older, demonstrating outcomes comparable to those observed in younger patients. CAR-T cell therapy should be not withheld for elderly patients with r/r DLBCL.

Online searches for hepatocellular carcinoma drugs mirror prescription trends across specialties and changes in guideline recommendations

Background & aims

The treatment options for systemically progressed hepatocellular carcinoma (HCC) have significantly expanded in recent years. In this study, we aimed to evaluate the potential of Google searches as a reflection of prescription rates for HCC drugs in the United States (US).

Methods

We conducted an in-depth analysis of US prescription data obtained from the IQVIA National Prescription Audit (NPA) and corresponding Google Trends data from January 2017 to December 2022. We focused on drugs used in the first line and second or later treatment lines for HCC, collecting data on their prescriptions and search rates. Search volumes were collected as aggregated search queries for both generic drugs and their respective brand names.

Results

During the study period from Q1 2017 to Q4 2022, monthly prescriptions for drugs used in HCC treatment showed an 173% increase (from 1253 to 3422). Conversely online searches increased by 3.5% (from 173 to 179 per 10 million searches). Notably, strong correlations were observed between search interest and prescriptions for newer drugs, which indicates increasing usage, while older drugs with declining usage displayed limited correlation. Our findings suggest a growing role of non-physician professions in managing systemically progressed HCC within the US healthcare system, although oncologists remained primarily responsible for drug prescriptions.

Conclusions

In conclusion, online search monitoring can offer the potential to reflect prescription trends specifically related to the treatment of HCC. This approach provides a swift and accessible means of evaluating the evolving landscape of HCC treatment.

Activity of tafasitamab in combination with rituximab in subtypes of aggressive lymphoma

Background

Despite recent advances in the treatment of aggressive lymphomas, a significant fraction of patients still succumbs to their disease. Thus, novel therapies are urgently needed. As the anti-CD20 antibody rituximab and the CD19-targeting antibody tafasitamab share distinct modes of actions, we investigated if dual-targeting of aggressive lymphoma B-cells by combining rituximab and tafasitamab might increase cytotoxic effects.

Methods

Antibody single and combination efficacy was determined investigating different modes of action including direct cytotoxicity, antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) in in vitro and in vivo models of aggressive B-cell lymphoma comprising diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL).

Results

Three different sensitivity profiles to antibody monotherapy or combination treatment were observed in in vitro models: while 1/11 cell lines was primarily sensitive to tafasitamab and 2/11 to rituximab, the combination resulted in enhanced cell death in 8/11 cell lines in at least one mode of action. Treatment with either antibody or the combination resulted in decreased expression of the oncogenic transcription factor MYC and inhibition of AKT signaling, which mirrored the cell line-specific sensitivities to direct cytotoxicity. At last, the combination resulted in a synergistic survival benefit in a PBMC-humanized Ramos NOD/SCID mouse model.

Conclusion

This study demonstrates that the combination of tafasitamab and rituximab improves efficacy compared to single-agent treatments in models of aggressive B-cell lymphoma in vitro and in vivo.

Allogeneic hematopoietic stem cell transplantation for NK/T-cell lymphoma: an international collaborative analysis

Natural killer/T-cell lymphomas (NKTCL) represent rare and aggressive lymphoid malignancies. Patients (pts) with relapsed/refractory disease after Asparaginase (ASPA)-based chemotherapy have a dismal prognosis. To better define the role of allogeneic hematopoietic stem cell transplantation (allo-HSCT), we conducted a retrospective analysis of data shared with the European Society for Blood and Marrow Transplantation (EBMT) and cooperating Asian centers. We identified 135 pts who received allo-HSCT between 2010 and 2020. Median age was 43.4 years at allo-HSCT, 68.1% were male. Ninety-seven pts (71.9 %) were European, 38 pts (28.1%) Asian. High Prognostic Index for NKTCL (PINK) scores were reported for 44.4%; 76.3% had >1 treatment, 20.7% previous auto-HSCT, and 74.1% ASPA-containing regimens prior to allo-HSCT. Most (79.3%) pts were transplanted in CR/PR. With a median follow-up of 4.8 years, 3-year progression-free(PFS) and overall survival were 48.6% (95%-CI:39.5-57%) and 55.6% (95%-CI:46.5-63.8%). Non-relapse mortality at 1 year was 14.8% (95%-CI:9.3-21.5%) and 1-year relapse incidence 29.6% (95%-CI:21.9-37.6%). In multivariate analyses, shorter time interval (0-12 months) between diagnosis and allo-HSCT [HR = 2.12 (95%-CI:1.03-4.34); P = 0.04] and transplantation not in CR/PR [HR = 2.20 (95%-CI:0.98-4.95); P = 0.056] reduced PFS. Programmed cell death protein 1(PD-1/PD-L1) treatment before HSCT neither increased GVHD nor impacted survival. We demonstrate that allo-HSCT can achieve long-term survival in approximately half of pts allografted for NKTCL.

Online searches for SGLT-2 inhibitors and GLP-1 receptor agonists correlate with prescription rates in the United States: An infodemiological study

Several clinical trials have demonstrated that many SGLT-2 inhibitors (SGLT2i) and GLP-1 receptor agonists (GLP-1 RA) can reduce the risk of cardiovascular events in patients with Type 2 diabetes and atherosclerotic cardiovascular disease. Recent reports indicate an underutilization of new cardiometabolic drugs, including SGLT2i and GLP-1 RA. We aimed to evaluate the use of online search volumes to reflect United States prescription rates. A repeated cross-sectional analysis of Google search volumes and corresponding data from the IQVIA National Prescription Audit (NPA) of pharmacy dispensing of newly prescribed drugs was performed. Monthly data for online searches and prescription between January 1, 2016 and December 31, 2021 were collected for selected SGLT2i and GLP-1 RA. Prescription data for drugs classes (SGLT2i and GLP-1 RA) and individual drugs were calculated as the total of queried data for branded drug names. Trends were analyzed for visual and quantitative correlation as well as predictive patterns. Overall, online searches increased by 157.6% (95% CI: 142.2-173.1%) and 295.2% (95% CI: 257.7-332.6%) for SGLT2i and GLP-1RA between 2016 and 2021. Prescription rates raised by 114.6% (95% CI: 110.8-118.4%) and 221.0% (95% CI: 212.1-229.9%) for SGLT2i and GLP-1RA for this period. Correlation coefficients (range 0.86-0.99) were strongest for drugs with growing number of prescriptions, for example dapagliflozin, empagliflozin, ertugliflozin, dulaglutide, and semaglutide. Online searches might represent an additional tool to monitor the utilization trends of cardiometabolic drugs. Associations were strongest for drugs with reported cardioprotective effect. Thus, trends in online searches complement conventionally acquired data to reflect and forecast prescription trends of cardiometabolic drugs.

Clinical relevance of molecular characteristics in Burkitt lymphoma differs according to age

While survival has improved for Burkitt lymphoma patients, potential differences in outcome between pediatric and adult patients remain unclear. In both age groups, survival remains poor at relapse. Therefore, we conducted a comparative study in a large pediatric cohort, including 191 cases and 97 samples from adults. While TP53 and CCND3 mutation frequencies are not age related, samples from pediatric patients showed a higher frequency of mutations in ID3, DDX3X, ARID1A and SMARCA4, while several genes such as BCL2 and YY1AP1 are almost exclusively mutated in adult patients. An unbiased analysis reveals a transition of the mutational profile between 25 and 40 years of age. Survival analysis in the pediatric cohort confirms that TP53 mutations are significantly associated with higher incidence of relapse (25 ± 4% versus 6 ± 2%, p-value 0.0002). This identifies a promising molecular marker for relapse incidence in pediatric BL which will be used in future clinical trials.

Association of Online Search Trends With Vaccination in the United States: June 2020 Through May 2021

Stagnating COVID-19 vaccination rates and vaccine hesitancy remain a threat to public health. Improved strategies for real-time tracking and estimation of population-level behavior regarding vaccinations are needed. The aim of this study was to evaluate whether online search trends for COIVD-19 and influenza mirror vaccination rates. State-level weekly fraction of online searches for top vaccination-related search terms and CDC vaccination data were obtained from June 1, 2020, to May 31, 2021. Next, trends in online search and vaccination data for COVID-19 and influenza were analyzed for visual and quantitative correlation patterns using Spearman’s rank correlation analysis. Online searches in the US for COVID-19 vaccinations increased 2.71-fold (95% CI: 1.98-3.45) in the 4 weeks after the FDA emergency authorization compared to the precedent 4 weeks. In March-April 2021, US online searches reached a plateau that was followed by a decline of 83.3% (95% CI: 31.2%-135.3%) until May 31, 2021. The timing of peaks in online searches varied across US states. Online searches were strongly correlated with vaccination rates (r=0.71, 95% CI: 0.45 - 0.87), preceding actual reported vaccination rates in 44 of 51 states. Online search trends preceded vaccination trends by a median of 3.0 weeks (95% CI: 2.0-4.0 weeks) across all states. For influenza vaccination searches, seasonal peaks in September-October between 2016-2020 were noted. Influenza search trends highly correlated with the timing of actual vaccinations for the 2019-2020 (r=0.82, 95% CI: 0.64 – 0.93) and 2020-2021 season (r=0.91, 95% CI: 0.78 – 0.97). Search trends and real-world vaccination rates are highly correlated. Temporal alignment and correlation levels were higher for influenza vaccinations; however, only online searches for COVID-19 vaccination preceded vaccination trends. These findings indicate that US online search data can potentially guide public health efforts, including policy changes and identifying geographical areas to expand vaccination campaigns.

Coronary artery calcium is associated with long-term mortality from lung cancer: Results from the Coronary Artery Calcium Consortium

BACKGROUND AND AIMS

Coronary artery calcium (CAC) scores have been shown to be associated with CVD and cancer mortality. The use of CAC scores for overall and lung cancer mortality risk prediction for patients in the Coronary Artery Calcium Consortium was analyzed.

METHODS

We included 55,943 patients aged 44-84 years without known heart disease from the CAC Consortium. There were 1,088 cancer deaths, among which 231 were lung cancer, identified by death certificates with a mean follow-up of 12.2 ± 3.9 years. Fine-and-Gray competing-risk regression was used for overall and lung cancer-specific mortality, accounting for the competing risk of CVD death and after adjustment for CVD risk factors. Subdistribution hazard ratios (SHR) were reported.

RESULTS

The mean age of all patients was 57.1 ± 8.6 years, 34.9% were women, and 89.6% were white. Overall, CAC was strongly associated with cancer mortality. Lung cancer mortality increased with increasing CAC scores, with rates per 1000-person years of 0.2 (95% CI: 0.1-0.3) for CAC = 0 and 0.8 (95% CI: 0.6-1.0) for CAC ≥400. Compared with CAC = 0, hazards were increased for those with CAC ≥400 for lung cancer mortality [SHR: 1.7 (95% CI: 1.2-2.6)], which was driven by women [SHR: 2.3 (95% CI: 1.1-4.8)], but not significantly increased for men. Risks were higher in those with positive smoking history [SHR: 2.2 (95% CI: 1.2-4.2)], with associations driven by women [SHR: 4.0 (95% CI: 1.4-11.5)].

CONCLUSIONS

CAC scores were associated with increased risks for lung cancer mortality, with strongest associations for current and former smokers, especially in women. Used in conjunction with other clinical variables, our data pinpoint a potential synergistic use of CAC scanning beyond CVD risk assessment for identification of high-risk lung cancer screening candidates.

Internet Search Trends Relevant to Interventional Oncology: A Google Trends Study (2004-2020)

Interventional Radiology (IR) procedures addressing cancer have been grouped in the subspecialty of interventional oncology and represent an important component of modern multidisciplinary cancer care. This study pinpoints temporal and geographical trends of public online searches for terms related to the field, as well as IR-related cancer therapies. Google Trends data were analyzed for long-term (2004-2020) trends in the United States and worldwide. Overall, search interest for IR increased throughout the United States but decreased globally. Specific search volumes for cancer-related IR techniques such as radioembolization and chemoembolization therapies increased by 2.8- and 2.5-fold, respectively, in the United States, whereas the search volumes for ablation techniques remained steady or decreased. Future research and advocacy may focus on increasing public awareness of the field.

The role of autologous stem cell transplantation (ASCT) in aggressive B-cell lymphomas: real-world data from a retrospective single-center analysis

Patients with high-risk or relapsed aggressive B-cell lymphomas are characterized by poor prognosis. High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) can induce durable remissions in these patients and is potentially curative. Two hundred forty-seven patients with aggressive B-cell lymphomas treated with high-dose chemotherapy and ASCT, either as consolidation after first-line therapy or after salvage therapy for relapsed disease, between 2002 and 2019 at the University Hospital Muenster, were analyzed. The median follow-up of surviving patients was 36 months (range 0–163). Progression-free survival (PFS) and overall survival (OS) after 3 years was 63% and 68%, respectively. After ASCT, 28% of all patients experienced a relapse. The cumulative incidence of non-relapse mortality at day 100 after ASCT was 4%. Multivariate analysis identified remission status at ASCT, age at ASCT, and the numbers of infused CD34⁺ cells as independent prognostic factors for both PFS and OS. Patients with mantle cell lymphoma (MCL) or primary CNS lymphoma (PCNSL) treated with ASCT in first-line had a superior OS and PFS when compared to patients treated with ASCT in relapsed disease. For patients with diffuse large B-cell lymphoma (DLBCL) and Hodgkin lymphoma (HL), early relapse (< 12 months) after first-line therapy showed a trend towards an inferior PFS and OS. Deaths after ASCT were predominantly caused by lymphoma relapse and/or progression (64%) or due to infections (23%). In conclusion, high-dose chemotherapy followed by ASCT in the era of novel targeted agents remains a feasible and effective approach for patients with high-risk or relapsed aggressive B-cell lymphomas. Remission status and age at ASCT, and the number of infused stem cells were of prognostic relevance.

Understanding myocardial infarction trends during the early COVID-19 pandemic: an infodemiology study

During the first months of the coronavirus disease 2019 (COVID‐19) pandemic in early 2020, Google Trends data in the United States showed a strong increase in search query frequency for chest pain symptoms despite a concurrent decrease in search interest for myocardial infarction. This suggests a reduced attention to acute coronary syndrome (ACS) and chest pain as its main symptom during this time period. These observations could help explain why cardiovascular mortality rose dramatically despite a strong decrease in hospitalisation rates for ACS.

Coronary artery calcium is associated with increased risk for lung and colorectal cancer in men and women: the Multi-Ethnic Study of Atherosclerosis (MESA)

AIMS

This study explored the association of coronary artery calcium (CAC) with incident cancer subtypes in the Multi-Ethnic Study of Atherosclerosis (MESA). CAC is an established predictor of cardiovascular disease (CVD), with emerging data also supporting independent predictive value for cancer. The association of CAC with risk for individual cancer subtypes is unknown.

METHODS AND RESULTS

We included 6271 MESA participants, aged 45-84 and without known CVD or self-reported history of cancer. There were 777 incident cancer cases during mean follow-up of 12.9 ± 3.1 years. Lung and colorectal cancer (186 cases) were grouped based on their strong overlap with CVD risk profile; prostate (men) and ovarian, uterine, and breast cancer (women) were considered as sex-specific cancers (in total 250 cases). Incidence rates and Fine and Gray competing risks models were used to assess relative risk of cancer-specific outcomes stratified by CAC groups or Log(CAC+1). The mean age was 61.7 ± 10.2 years, 52.7% were women, and 36.5% were White. Overall, all-cause cancer incidence increased with CAC scores, with rates per 1000 person-years of 13.1 [95% confidence interval (CI): 11.7-14.7] for CAC = 0 and 35.8 (95% CI: 30.2-42.4) for CAC ≥400. Compared with CAC = 0, hazards for those with CAC ≥400 were increased for lung and colorectal cancer in men [subdistribution hazard ratio (SHR): 2.2 (95% CI: 1.1-4.7)] and women [SHR: 2.2 (95% CI: 1.0-4.6)], but not significantly for sex-specific cancers across sexes.

CONCLUSION

CAC scores were associated with cancer risk in both sexes; however, this was stronger for lung and colorectal when compared with sex-specific cancers. Our data support potential synergistic use of CAC scores in the identification of both CVD and lung and colorectal cancer risk.

Multidisciplinary prevention and management strategies for colorectal cancer and cardiovascular disease

Colorectal cancer (CRC) and cardiovascular disease (CVD) are leading causes of morbidity and mortality worldwide. Their numerous shared and modifiable risk factors underscore the importance of effective prevention strategies for these largely preventable diseases. Conventionally regarded as separate disease entities, clear pathophysiological links and overlapping risk factors represent an opportunity for synergistic collaborative efforts of oncologists and cardiologists. In addition, current CRC treatment approaches can exert cardiotoxicity and thus increase CVD risk. Given the complex interplay of both diseases and increasing numbers of CRC survivors who are at increased risk for CVD, multidisciplinary cardio-oncological approaches are warranted for optimal patient care from primary prevention to acute disease treatment and long-term surveillance.

Temporal Trends and Interest in Coronary Artery Calcium Scoring Over Time: An Infodemiology Study

Objective

To evaluate interest in coronary artery calcium (CAC) among the general public during the past 17 years and to compare trends with real-world data on number of CAC procedures performed.

Methods

We used Google Trends, a publicly available database, to access search query data in a systematic and quantitative fashion to search for CAC-related key terms. Search terms included calcium test, heart score, calcium score, coronary calcium, and calcium test score. We accessed Google Trends in January 2021 and analyzed data from 2004 to 2020.

Results

From 2004 to December 31, 2020, CAC-related search interest (in relative search volume) increased continually worldwide (+201.9%) and in the United States (+354.8%). Three main events strongly influenced search interest in CAC: reports of a CAC scan of the president of the United States led to a transient 10-fold increase in early January 2018. American College of Cardiology/American Heart Association guideline release led to a sustained increase, and lockdown after the global pandemic due to COVID-19 led to a transient decrease. Real-world data on performed CAC scans showed an increase between 2006 and 2017 (+200.0%); during the same time period, relative search volume for CAC-related search terms increased in a similar pattern (+70.6%-1511.1%). For the search term coronary calcium scan near me, a potential representative of active online search for CAC scanning, we found a +28.8% increase in 2020 compared with 2017.

Conclusion

Google Trends, a valuable tool for assessing public interest in health-related topics, suggests increased overall interest in CAC during the last 17 years that mirrors real-world usage data. Increased interest is seemingly linked to reports of CAC testing in world leaders and endorsement in major guidelines.

The role of PI3K inhibitors in the treatment of malignant lymphomas

Deregulated phosphatidylinositide 3-kinase (PI3K) signaling plays a crucial role in the biology of different lymphoma entities leading to the proliferation and survival of the malignant cells. Due to novel treatment options and modern supportive care, the outcome of patients with lymphomas has significantly improved in the past years. However, patients with relapsed or refractory disease still have a limited prognosis. PI3K inhibitors represent a modern and effective therapeutic option for patients with different types of lymphoma. However, the efficacy of PI3K inhibitors varies among lymphoma entities. Additionally, severe toxicity including infectious and autoimmune complications leading to therapy-related deaths has been observed. Next-generation PI3K inhibitors show promising efficacy and manageable toxicity profiles. Future research might identify effective combinatorial therapy approaches for PI3K inhibitors to further improve response rates. This review discusses the most recent developments in the field of PI3K inhibition in different subtypes of lymphoma.

The Receptor Tyrosine Kinase RON and Its Isoforms as Therapeutic Targets in Ewing Sarcoma

The receptor tyrosine kinase (RTK) RON is linked to an aggressive metastatic phenotype of carcinomas. While gaining interest as a therapeutic target, RON remains unstudied in sarcomas. In Ewing sarcoma, we identified RON among RTKs conferring resistance to insulin-like growth factor-1 receptor (IGF1R) targeting. Therefore, we explored RON in pediatric sarcoma cell lines and an embryonic Tg(kdrl:mCherry) zebrafish model, using an shRNA-based approach. To examine RON–IGF1R crosstalk, we employed the clinical-grade monoclonal antibody IMC-RON8, alone and together with the IGF1R-antibody IMC-A12. RON silencing demonstrated functions in vitro and in vivo, particularly within micrometastatic cellular capacities. Signaling studies revealed a unidirectional IGF1-mediated cross-activation of RON. Yet, IMC-A12 failed to sensitize cells to IMC-RON8, suggesting additional mechanisms of RON activation. Here, RT-PCR revealed that childhood sarcomas express short-form RON, an isoform resistant to antibody-mediated targeting. Interestingly, in contrast to carcinomas, treatment with DNA methyltransferase inhibitor did not diminish but increased short-form RON expression. Thus, this first report supports a role for RON in the metastatic progression of Ewing sarcoma. While principal molecular functions appear transferrable between carcinomas, Ewing sarcoma and possibly more common sarcoma subtypes, RON highlights that specific regulations of cellular networks and isoforms require better understanding to successfully transfer targeting strategies.

The CXCR4 antagonist plerixafor (AMD3100) promotes proliferation of Ewing sarcoma cell lines in vitro and activates receptor tyrosine kinase signaling

BACKGROUND

The CXCR4 receptor antagonist plerixafor (AMD3100) is raising interest as an anti-cancer agent that disrupts the CXCL12-CXCR4 chemokine - receptor interaction between neoplastic cells and their microenvironment in tumor progression and metastasis. Here, we investigated plerixafor for anti-cancer activity in Ewing sarcoma, a rare and aggressive cancer of bone and soft tissues.

METHODS

We used a variety of methods such as cell viability and migration assays, flow cytometry, phospho-tyrosine arrays and western blotting to determine plerixafor effects on five characterized Ewing sarcoma cell lines and a low-passage culture in vitro.

RESULTS

Unexpectedly, plerixafor led to an increase in cell viability and proliferation in standard cell growth conditions, and to chemotactic migration towards plerixafor. Exploring potential molecular mechanisms underlying this effect, we found that Ewing sarcoma cell lines divided into classes of high- and low-level CXCR4 surface expression. Proliferative plerixafor responses were observed in both groups, maintained despite significant CXCR4 down-regulation or inhibition of Gαi-protein signal transduction, and involved activation of multiple receptor tyrosine kinases (DDR2, MERTK, MST1R, NTRK1, RET), the most prominent being platelet-derived growth factor receptor beta (PDGFRB). PDGFRB was activated in response to inhibition of the CXCL12-CXCR4 axis by plerixafor and/or pertussis toxin (Gαi-protein inhibitor). Dasatinib, a multi-kinase inhibitor of both PDGFRB and the CXCR4 downstream kinase SRC, counteracted this activation in some but not all cell lines.

CONCLUSION

These data suggest a feedback interaction between the CXCR4 chemokine receptor and RTK signaling cascades that elicits compensatory cell survival signaling and can shift the net effect of plerixafor towards proliferation. PDGFRB was identified as a candidate driver RTK and potential therapeutic co-target for CXCR4 in Ewing sarcoma. Although as yet limited to in vitro studies, these findings call for further investigation in the cancer - microenvironment interplay in vivo.

Receptor tyrosine kinase gene expression profiles of Ewing sarcomas reveal ROR1 as a potential therapeutic target in metastatic disease

Receptor tyrosine kinases (RTKs) have provided molecular targets for the development of novel, prognosis-improving agents in many cancers; however, resistances to these therapies occur. On the cellular level, one resistance mechanism is attributed to functional RTK redundancies and compensatory cross-signaling, leading to perception of RTKs as signaling and target networks. To provide a basis for better exploitation of this network in Ewing sarcoma, we generated comprehensive qPCR gene expression profiles of RTKs in Ewing sarcoma cell lines and 21 untreated primary tumors. Key findings confirm broad-spectrum RTK expressions with potential for signaling redundancy. Profile analyses with regard to patient risk-group further revealed several individual RTKs of interest. Among them, VEGFR3 and TIE1 showed high-level expressions and also were suggestive of poor prognosis in localized tumors; underscoring the relevance of angiogenic signaling pathways and tumor-stroma interactions in Ewing sarcoma. Of note, compared to localized disease, tumors derived from metastatic disease were marked by global high-level RTK expressions. Nine individual RTKs were significantly over-expressed, suggesting contributions to molecular mechanisms of metastasis. Of these, ROR1 is being pursued as therapeutic target in leukemias and carcinomas, but un-characterized in sarcomas. We demonstrate expression of ROR1 and its putative ligand Wnt5a in Ewing sarcomas, and of an active ROR1 protein variant in cell lines. ROR1 silencing impaired cell migration in vitro. Therefore, ROR1 calls for further evaluation as a therapeutic target in metastatic Ewing sarcoma; and described as a pseudo-kinase with several isoforms, underlines these additional complexities arising in our understanding of RTK signaling networks.